1. Field of the Invention
This invention relates to an image correction apparatus and method for applying color correction processing (color conversion processing) to digital image data, and to a program that causes a computer to execute this image correction processing.
2. Description of the Related Art
When a color print is created using digital image data obtained by reading image data, which has been recorded on photographic negative film or reversible film, as by a scanner, or digital image data acquired by a digital camera or mobile telephone equipped with a camera, there are instances where the color print is created upon subjecting the digital image data to color correction processing that corrects color balance in such a manner that the impression obtained will be similar to that of the scene when the picture was taken.
The specification of Japanese Patent Application Laid-Open No. 2000-182043 (Patent Reference 1) proposes detecting an image, which represents, e.g., the face of a person, based upon entered image data, obtaining coefficients k1, k2 whereby the color of the image representing the detected face of the person is made a desired color (skin tone), and subjecting the overall image data to color conversion processing (color correction) using the coefficients k1, k2 obtained.
Patent Reference 1 assumes that the image data to be processed is image data representing a color image; it does not take into account a case where image data to be processed does not represent a color image, e.g., a case where the data is image data representing a monochrome image. If an image representing the face of a person contained in the image to be processed is a monochrome image, the color of the image representing the face of the person that is the monochrome image will be color-corrected to the skin-tone color. Owing to such color correction processing, an image that is widely different from the original image is produced.
Further, Patent Reference 1 does not take into account the relationship between brightness of an image representing the face of a person before color conversion processing and brightness of the image representing the face of the person after color conversion processing. In Patent Reference 1, color conversion processing is applied to the entirety of the image data in such a manner that the color (skin tone) of the image data of the face area will have a predetermined target chromaticity value. The brightness of the face of the person in the image represented by the image data after the color conversion comes to have a brightness that is based upon the predetermined target chromaticity value. Basically, therefore, the brightness of the image representing the face of the person before the color conversion and the brightness of the image representing the face of the person after the color conversion do not agree.